Milk is a pale liquid produced by the mammary glands of cows. It can be a primary source of nutrition for infants before they are able to digest other types of food. Early-lactation cow milk contains bovine colostrum, which carries the mother's antibodies to young calves and can reduce the risk of many bovine diseases. It contains many other nutrients, including protein and lactose.

Dairy farms produced about 730 million tonnes of milk in 2011, from 260 million dairy cows.